In prior art circuit breakers as exemplified in U.S. Pat. No. 3,057,983, there is disclosed an arrangement of a plurality of serially related interrupters. Therein the high pressure reservoir and a blast valve mechanism are disposed adjacent one end of the arc extinguishing assembly which bridges the space between spaced terminal bushings. Support of the interrupter assembly is obtained from the terminal bushings. The general operation of the above-identified interrupter is such that during the opening operation a single blast valve opens to allow the gas from the high pressure chamber to blast through a plurality of blast tubes and into the interrupting units. In other words, the interrupter furthest from the high pressure chamber is expected to receive its share of the gas blast as soon as the interrupter which is closest to the high pressure source receives its share. The pull-rods or operating rods are of ladder shape construction, arranged on each side of the interrupter structure. This arrangement necessitates cross arms which adds to the mass that the acceleration spring must move. In U.S. Pat. Nos. 3,852,549 and 3,891,862, a pull-rod arrangement which is external to the enclosure is shown which is, of course, even more remote from the mass which the acceleration spring must move. With these disclosed arrangements elaborate shock absorbing devices must be supplied to reduce the shock load on the structure and prevent damage to the equipment.
Also in the above-mentioned patents, the serially related interrupter is not of modular construction and there is nothing disclosed therein which operates on the interrupters to counteract the effect of tensioning forces that are applied to the interrupter through the pull-rods in their closing and opening operation.
The concept provides truly modular design with each interrupter being a complete, independent operating unit not dependent on any other unit. Thus, it is not necessary to reengineer and retest the design every time the number of interrupters per phase is changed as has been necessary with prior art structures.
With known gas insulated circuit breakers, redesign and testing has been necessary with a change in the number of interrupters per phase to assure that the opening time is sufficiently fast to achieve: (a) the short interrupting time demanded and (b) that the moving parts are stopped at the ends of the opening stroke without excessive rebound and stressing of the moving parts. It is also noted that with known gas insulated circuit breakers the pull-rods and linkages from the operating mechanism to each of the interrupters must be designed to take both compressive loads and tensile loads. To withstand the compressive loads without buckling, the long pull-rods are designed several times larger in cross-section of pull-rods that need only stand tensile loads. This increases the weight of the pull-rods which, in turn, requires much greater forces to accelerate them and also to stop them. These additional forces also impart greater bearing loads and greater loads on the supports. Greater friction is also encountered at each bearing. Thus, the operator mechanism must be designed larger and stronger to accommodate the larger masses, forces and friction that has previously been mentioned. It is also known that with prior art gas-insulated circuit breakers the moving contacts inside the pole unit will experience oscillations at the ends of the strokes with the acceleration and the stopping means being located outside of the interrupter because of the elasticity of the linkages in between.
The present invention provides advantages not obtainable in the past. One such advantage obtains by providing individual opening accelerating and individual opening and closing stopping means within each interrupter. In this manner, the pull-rods between interrupters are under tension in both directions of movement and thus require minimum cross-section and mass. Bearing size, acceleration forces and operating stresses are maintained at a minimum. The size of the operating mechanism is minimized and contacts can be opened and closed in minimum time. With the present concept, the interrupters are truly modular wherein the same interrupter structure without change is capable of being used in many circuit voltage ratings. Proving the interrupter ratings of a wide range of circuit breakers can be achieved with a minimum of expensive short circuit interrupting tests. Included in the concept are stabilizing means in the form of compression members both between the enclosure end and the adjacent interrupter and between interrupters. With this concept, volume manufacturing minimum cost in material stocking and inventory.
A general object of this invention is to provide interrupters for gas-insulated circuit breakers which can be used either one per phase or in a greater number per phase as required by the magnitude of the phase voltage.
Another object of this invention is to provide a pull-rod arrangement which locates the pull-rod in close proximity to the mass that it will operate.
Still another object of this invention is to provide a modular interrupter structure for a gas insulated circuit breaker incorporating accelerating and stopping means sufficient for each interrupter within the circuit breaker module.
A further object of this invention is to provide internal support for the interrupters within the enclosure that counteracts the force of the tension on the pull-rods and also assists the interrupter support is carrying the interrupter structure.
Yet another object of the present invention is to provide motion transmitting mechanism which is in tension at all times so that the mass of the structure may be reduced and relatively lightweight materials may be utilized.
A still further object of the present invention is to provide improved mechanism for controlling the velocity of movement of the contacts which will also serve as a shock absorbing means.